Air filter assembly

ABSTRACT

A compact lightweight air filtration system is disclosed. The air filtration system includes a hydrophobic particulate/coalescing filter and a cleanable ozone converter housed in a housing with an inlet and an outlet. Air flowing from the inlet to the outlet passes through the particulate/coalescing filter element and then the cleanable ozone converter to remove particulates, aerosols, liquids, and ozone.

RELATED APPLICATIONS

The present patent document claims the benefit of the filing date under35 U.S.C. §119(e) of Provisional U.S. Patent Application Ser. No.62/313,898, filed Mar. 28, 2016, which is hereby incorporated byreference.

BACKGROUND

1. Technical Field

Embodiments of the invention relate to air filtration and moreparticularly to air filtration with integrated particulate filtering,coalescing, and cleanable/reusable ozone conversion properties.

2. Background Information

Aircraft cabins may contain hundreds of passengers crowded into a smallspace for an extended period of time. The air within the aircraft cabinmay be polluted to various degrees by dust, pollens, lint, and smoke.The air is often recycled, such that a portion of the air is returned tothe cabin and mixed with fresh air.

To reduce the amount of pollutants, the cabin air is recirculatedthrough filters to reduce the amount of pollutants. Additionally, freshair is provided from an external source to supplement the recirculatedair. Commercial aircraft cabins and flight decks typically recirculateapproximately 50% of the cabin air and add approximately 50% fresh airfrom the external source. The external source of air assures that therecirculated portion does not endlessly recirculate, but is diluted andreplaced with outside air.

In addition to pollutants, there are other treatments that may beapplied to the air. For instance, oil mist may be present in therecirculated air or the fresh air, which should be removed beforesupplying the air to the cabin. Furthermore, ozone may be present atelevated concentrations in the atmosphere. Supplying the cabin with airhigh in ozone content may irritate the passengers breathing or causeother health risks.

Ideally, cabin air should be substantially free of particulate, oilmist, and ozone for the benefit of cabin passengers. To this end,airlines are currently equipped with filtrations systems and coalescingfilters for removing oil mist. Additionally, newer airlines may includeozone removal systems to lower the ozone levels in the cabin.

In addition to cabin air, there are other systems in an aircraft thatrequire filtered air low levels of ozone. For example, the fuel tanks ofmodern aircraft include fuel inerting systems for reducing the riskassociated with an explosion of the fuel in the tank. These systems maywork by replacing spent fuel with an inert gas such as nitrogen. Whilenitrogen is readily available from the ambient atmosphere, it is mixedwith oxygen that must be removed to obtain an inert gas. This may bedone through the use of an air separation module, as commonly known toone of skill in the art. The air separation module requires a source offiltered air substantially free of particulates, oil, liquids, and ozoneto extend the efficiency and life of the module.

While each of the described systems are generally effective for theirintended purposes, extra space and weight add to fuel costs and reducethe amount of fare paying cargo that an airline may transport.Therefore, each system may not be the optimal size, or other compromisesmay be made to reduce the weight or size.

It would be beneficial to treat cabin air in a manner that was at leastas effective as the described systems, while minimizing the cost, size,and weight of the systems required to treat the cabin air.

BRIEF SUMMARY

In one aspect a filter assembly is disclosed. The filter assemblyincludes a housing, a particulate/coalescing element, and a cleanableozone converter. The particulate/coalescing is disposed in the housingand includes a hydrophobic filtration media. The ozone cleanableconverter is disposed in the housing and includes a passageway have acatalytic interface surface. The filter assembly has a flow path throughthe housing that includes flowing through the particulate/coalescingelement and then through the cleanable ozone converter before exitingthe housing.

In some embodiments, the housing includes a manifold having an inlet andan outlet, and a filter bowl removably coupled to the manifold. In someembodiments the housing is cylindrical. In some embodiments, the flowpath flows from the manifold inlet into the particulate/coalescingelement and from the cleanable ozone converter into the manifold outlet.

In some embodiments, the filter assembly further includes a drain plugin a bottom of the manifold. In some embodiments, the manifold has aninner flange sized to receive the cleanable ozone converter and an outerflange sized to receive the filter element. In some embodiments, themanifold outlet extends to a central location of the manifold. In someembodiments, a V-band secures the filter bowl to the manifold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of an air filtration system.

FIG. 2 illustrates a cross section of the embodiment of FIG. 1.

FIG. 3 illustrates a manifold for the air filtrations system of FIG. 1.

FIG. 4 illustrates a top view of a filter element for the airfiltrations system of FIG. 1.

FIG. 5 illustrates a bottom view of the filter element for the airfiltration system of FIG. 1.

FIG. 6 illustrates a media pack layout of the filter element.

FIG. 7 illustrates a cleanable ozone converter for the air filtrationsystem of FIG. 1.

FIG. 8 illustrates an exploded view of the air filtration system of FIG.1.

DETAILED DESCRIPTION

In the following passages, different aspects of the invention aredefined in more detail. Each aspect so defined may be combined with anyother aspect or aspects unless clearly indicated to the contrary. Inparticular, any feature indicated as being preferred or advantageous maybe combined with any other feature or features indicated as beingpreferred or advantageous.

FIG. 1 illustrates an external view of an air filtration system 10. Theair filtration includes an inlet 12 for receiving a supply of untreatedair, and an outlet 14 for delivering treated air. Between the inlet 12and the outlet 14, the air filtration system 10 has three stages fortreating a flow of air between the inlet 12 and the outlet 14. The firststage removes liquids from the air, the second stage removesparticulates and aerosols, and the third stage removes ozone from thefiltered air. The air filtration system 10 includes a housing comprisinga manifold 18 having the inlet 12 and outlet 14, and a filter bowl 20for covering the internal components.

FIG. 2 illustrates a cross section of the air filtration system 10 ofFIG. 1. Arrows 16 signify a path for the flow of air from the inlet 12to the outlet 14. In operation, the air first flows into the manifold 18where it is directed into the filter bowl 20. Within the filter bowl 20is a filter element 22 and an annular space 24 which is defined by aninterior surface 26 of the filter bowl 20 and an exterior surface 28 ofthe filter element 22. The air flows from the manifold 18 and into theannular space 24, enveloping the filter element 22.

From the annular space 24, the air flows through the filter element 22,where stage 1 and stage 2 of the filtration process removes liquids,particulates, and aerosols. From the filter element 22, the air passesthrough a cleanable ozone converter 30 and back into the manifold 18,where it is directed out through the outlet 14.

FIG. 3 illustrates the manifold 18 of FIG. 2, separate from the othercomponents of the air filtration system 10. The manifold 18 hasprotrusions 32 at a base end having through holes 34 for mounting themanifold 18. The manifold 18 is circular in shape and has a centrallylocated ring 36 configured to receive the cleanable ozone converter 30and the filter element 22. The centrally located ring 36 has an innerflange 38 configured to receive a base of the cleanable ozone converter30, and an outer flange 40 configured to receive a base of the filteringelement 22.

FIG. 4 illustrates a top end of the filter element 22 separate from theremaining components of the air filtration system 10. FIG. 5 illustratesa bottom end of the filter element 22 separate from the remainingcomponents of the air filtration system 10. The filter element 22comprised of a porous, multilayer sheet of material that is folded intopleats and formed in a cylinder. The top of the cylinder is sized to fitin a protrusion of the filter bowl, while the base is sized to engagethe outer flange 40 of the manifold 18. Thus, when assembled, the filterelement 22 is held in place at the top end by the protrusion and at thebottom end by the outer flange 40. Air is only able to enter pass fromthe annular space 24 into the outlet of the manifold 18 by passingthrough the filter element 22.

In some embodiments, the base of the filter element 22 and/or the top ofthe filter element 22 may be formed of an elastic material suitable forforming a seal between the outer flange 40 and the protrusion of thefilter bowl. In some embodiments, a gasket may be used between sealingsurfaces of the filter bowl and the filter element 22 and/or themanifold 18 and the filter element 22.

FIG. 6 illustrates the filter element 22 showing pleats 50 and multiplelayers 52 and stages of filtration. The filter element 22 usesconventional filtration techniques to filter particulates in the airpassing through the filter element 22 including impingement,interception, diffusion, and straining. The filter element 22 may becomprised of fiber having a size and spacing selected for the desiredlevel of filtering.

In addition to the conventional filtering of particulates and aerosols,the layers of the filter element 22 are hydrophobic, either by way of acoating or the fibers themselves being hydrophobic. The filter element22 filters water droplets in the air passing through the filter in aconventional manner like it does for particulates and aerosols. However,because the fibers are hydrophobic, the water droplets captured on thefibers are unable to wet the surface. The water droplets then combine toform water droplets of increasing size, eventually dropping from thefilter element 22 and into the manifold 16.

FIG. 7 illustrates the cleanable ozone converter 30 separate from theremaining elements. The cleanable ozone converter 30 has passagewayspassing through the cleanable ozone converter 30 from an outer surface54 to a converter outlet 56, such that air flows through the cleanableozone converter 30 to reach the converter outlet 56. The passageways maybe formed by an open cell structure, a porous structure of the cleanableozone converter, rows of material having gaps there between, pelletshaving interstitial spaces between adjacent pellets, or other techniquesas known to one of skill in the art. The passageways increase thesurface area of the cleanable ozone converter 30 that interact with theair flowing through the cleanable ozone converter 30.

The cleanable ozone converter 30 contains a catalyst material such asplatinum, platinum alloy, or other catalyst materials as known in theart. The catalyst material increases the rate at which ozone containedin the air flow decomposes and reacts with atmospheric oxygen. Thepassageways in the cleanable ozone converter 30 may be coated with thecatalyst material rather than having a solid catalyst construction. Forexample, in one embodiment a corrosion resistant foil substrate coatedwith a slurry of platinum and iridium is used to form a honeycomb ofpassageways through the cleanable ozone converter 30. Such materials arecompatible to most known contaminants in a climate controlled operatingenvironment.

FIG. 8 illustrates the air filtration system 10 of FIG. 1 in an explodedview, showing the general assembly of the air filtration system 10. Themanifold 18 is generally mounted to a secure surface using theprotrusions 32, 34 at the base of the manifold. The filter bowl 20 isremovable to allow access to the interior of the air filtration system10. A V-band 60, or ring clamp secures the filter bowl 20 to themanifold 18 in a removable fashion. A removable insulation layer 62 maybe placed over the filter bowl 20 for insulation. The insulation layer62 has hook and loop fasteners for temporary attachment to the manifold18 or bowl 20, allowing the insulation layer 62 to be easily removed forservice. Other fasteners are possible such as snaps, button, zippers,and other means of temporary attachment.

The cleanable ozone converter 30 is housed on the inner flange of themanifold 18 with the filter element 22 surrounding the cleanable ozoneconverter 30; the filter element 22 being housed on the outer flange.Gaskets 64 may be placed between the filter bowl 20 and the manifold 18,the cleanable ozone converter 30 and the manifold 18, the filter bowl 20and the filter element 22, and the manifold 18 and the filter element22.

In use, liquid captured by the coalescing filter element 22 falls intothe manifold 18 when the droplets grow to suitable size. Drain plugs inthe bottom of the manifold 18 allow the liquid to drain out the bottomof the manifold 18. The drain plugs may be pressure sensitive, such thatthey only drain when a set inlet pressure is exceeded. For example, thedrain plugs might be closed when the filtration system is not in use,but when air is directed to the inlet, the increase in pressure maycause the drain valves to open, draining any liquid in the manifold.

The described filtrations system allows for a compact, lightweightdesign for the filtration of air and removal of ozone. In someembodiments, the design allows a complete filter assembly to be lessthan fourteen inches in height and less than one foot in diameter, whileweighing less than twenty pounds. Additionally, the filtration systemmay have a flow rate of between ten pounds per minute and thirty-twopounds per minute at one hundred fifty pounds per square inch ofpressure.

It should be understood that the described embodiment is a preferredembodiment and various changes and modifications to the presentlypreferred embodiment described herein will be apparent to those skilledin the art. For example, the air filter may have a different shape thanthat shown such as a box or other shape. Additionally, while it ispreferred that the outlet be coupled to the cleanable ozone converternear the center of the manifold, in some embodiments the outlet could bepositioned differently.

We claim:
 1. A filter assembly comprising: a housing; aparticulate/coalescing element disposed in the housing, theparticulate/coalescing comprising a hydrophobic filtration media; acleanable ozone converter disposed in the housing, the cleanable ozoneconverter comprising a passageway have a catalytic interface surface;and wherein the filter assembly has a flow path through the housing thatincludes flowing through the particulate/coalescing element and thenthrough the cleanable ozone converter before exiting the housing.
 2. Thefilter assembly of claim 1, wherein the housing comprises: a manifoldhaving an inlet and an outlet; and a filter bowl removably coupled tothe manifold.
 3. The filter assembly of claim 1, wherein the housing iscylindrical.
 4. The filter assembly of claim 2, wherein the flow pathflows from the manifold inlet into the particulate/coalescing elementand from the cleanable ozone converter into the manifold outlet.
 5. Thefilter assembly of claim 2, further comprising a drain plug in a bottomof the manifold.
 6. The filter assembly of claim 2, wherein the manifoldhas an inner flange sized to receive the cleanable ozone converter andan outer flange sized to receive the filter element.
 7. The filterassembly of claim 2, wherein the manifold outlet extends to a centrallocation of the manifold.
 8. The filter assembly of claim 2, wherein aV-band secures the filter bowl to the manifold.